New claim staked for metallic hydrogen

Some experts doubt report of creating elusive material

TIGHT SQUEEZE As scientists pressed hydrogen between two diamonds, it changed from transparent (left) to black (middle) and, finally, to a reflective state (right). That reflectivity indicates that the hydrogen transformed into a metal, researchers claim.

Ranga Dias, I.F. Silvera

A team of scientists may have given hydrogen a squeeze strong enough to turn it into a metal. But critics vigorously dispute the claim.

Researchers from Harvard University report that under extremely high pressures hydrogen became reflective — one of the key properties of a metal. The feat required compressing hydrogen to 4.9 million times atmospheric pressure, the scientists report online January 26 in Science.

If correct, the result would be the culmination of a decades-long search for a material that could have unusual properties such as superconductivity — the ability to conduct electricity without resistance.

But physicist Eugene Gregoryanz of the University of Edinburgh, who works on similar experiments, decries the study’s publication as a failure of the journal’s review process. Given the evidence presented

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